Sails

ABSTRACT

This invention is an improved sail which uses wedge-shaped panels on the luff with warp threads running the length of the wedges. By properly proportioning the wedges, luff tension is distributed through the centroid of the .[.jib.]. .Iadd.sail .Iaddend.triangle and thus controls draft position and leading edge flatness. The result is a broader wind range sail with longer optimum performance life.

SUMMARY

This invention is a new and improved jib for use on sailing yachts. Ajib is the forward-most sail, primarily used for sailing into the windon modern yachts.

The primary achievement of this new jib is improved speed into the windby reducing jib sail distortion. Sail distortion is less, due to thereduced dependence on headstay support in the plane of the sail.

Another object of this invention is to provide a longer-lasting sail,through the improved design which orients the strongest dimension ofcloth along lines of greatest stress in the luff. Many jibs after aseason of use will not work well going to windward due to luff biasbreakdown.

Another object is to provide optimum performance over a greater windspeed range for any given weight of sailcloth.

DESCRIPTION OF DRAWINGS

FIGS. 1 through 4 are examples of prior art listed in the referencesection.

FIG. 5 is the drawings of my invention illustrating the improved luffconfiguration.

FIG. 5A is an exploded view of the sail taken at 22 of FIG. 5.

All figures are oriented the same with Luff (1), Leech (2), and Foot (3)so labeled in FIG. 1.

PROBLEMS OF PRIOR ART

All jibs used today attach to a high-strength metal cable or rod alongtheir luff (1) side and are firmly attached at their head and tackcorners at the ends of the luff side. The resultant wind force actingnearly through the sail centroid and nearly perpendicular to the surfacepulls inward on all perimeter points of the sail and causes the luff tosag into the sail, even when attached to a taut cable. A thirty-footluff cable with thousands of pounds of tension cannot retain a straightline and will sag many inches into the sail. It is this sag, variablewith the wind velocity, which causes distortion in prior art. The sailscan only be cut for one value of headstay sag.

With the development of high-strength fibers such as nylon, polyester(dacron) and now kevlar, the problems of sail-making have changed..Iadd.The warp and weft of the sail cloth are the directions of greaterstrength in tension of the material and therefore provide the lines ofdirectional stability as compared to the substantially lower tensionstrength and stability in any bias direction of the sail material..Iaddend.Warp and weft strength is, in most cases, sufficient and sailsdegenerate due to luff bias breakdown long before leech and footelongation problems occur. It is proven that in racing yachts today,performance in heavier winds is improved by intentional easing of leechtension by changing the direction of sheet force, (11), shown in FIG. 5.

Luff breakdown, coupled with headstay sag, causes undesirable changes insail draft. Atempts by the crew to restore designed-in new shape bychanging luff tension usually results in further distortion andworsening windward performance.

DETAILED DESCRIPTION

My invention is shown in FIG. 5 and is an improved jib sail for sailingyachts. Referring to FIG. 5, the following names and numerals of sailparts will be used in this specification and claims. 1 is the luff side.Iadd.or edge .Iaddend.of the sail and is the leading edge, while 2 isthe leech side .Iadd.or edge .Iaddend.which is the trailing edge. Thebottom side or .Iadd.edge .Iaddend.is 3, the foot. The head corner is19, with halyard force 9 applied, the forward lower tack corner is 20,with force 10 applied to the box, and the rear clew corner is 21, withrope sheeting force 11 applied to the deck. Sail luff is attached to asteel cable headstay, which is parallel to the luff and itself attachesfirmly to bow and mast. .Iadd.As used herein, luff shall mean asupported sail edge, unlike the unsupported edge of a spinnaker..Iaddend.When sailing under wind stress, the force exerted on the sailluff by this cable is 12. 22 is a point near the sail centroid where theresultant wind force applies pressure perpendicular to the sail surface.The resultant wind force is the vector sum of all forces acting on thesail surface. The unique benefits of this jib are embodied in thetriangular panels 5, 6, 7 and 8 which form the luff region of the sail.Four panels .Iadd.of woven sail material .Iaddend.are shown, but more orless may be used. Within these cloth panels, warp threads are orientedalong directions 15, 16, 17 and 18, respectively.Iadd., which are thelines of substantial directional stability of the sailmaterial.Iaddend..

FIG. 5A is an exploded view of warp threads 16 and 18 and weft threadswithin panels 6 and 8 at 22.

This new luff region extends from the luff 1 into the sail areaapproximately 30% of the horizontal sail arc at the widest portion. Asshown in FIG. 5, the upper luff area consists of panels 5 and 6, thelower luff area contains panels 7 and 8. The seam line forming thejuncture of upper luff area and lower luff area extends approximatelythrough jib triangle centroid. This centroid is approximately 1/3 of theheight of the jib up from the jib base.

Wind forces on an equivalent sail model will act through 22 and will beperpendicular to the surface. Said wind force is opposed by forces 9, 10and 11 acting through the three corners 19, 20 and 21; it is alsoopposed by force 12, exerted on the luff by the headstay cable as thiscable attempts to support the sail luff. With prior art the force 12 hasa major influence on sail shape and is actually spread out by multipleheadstay attachments. (For analysis, 12 is represented as a singleforce.) The stronger the sail cloth .Iadd.or material in the directionalong lines 15, 16, 17 and 18.Iaddend., the less load will occur at 12and the greater load will be at 9 and 10. Sides 2 and 3, the leech andfoot, cannot oppose said wind force, as they are unsupported sides.

In the improved jib of FIG. 5, panels 5, 6, 7 and 8 are arranged so asto transfer wind forces directly to head 19 and tack 20 from thecentroid, at or near 22, by aligning the strong warp threads 15, 16, 17and 18 parallel to these forces .Iadd.which produce lines of principletension stress extending between the vicinity of the head corner 19 andthe vicinity of the tack corner 20.Iaddend.. This alignment is importantbecause warp strength is 2 to 10 times greater than bias strength.Iadd.in woven cloth and for any sail material it is preferred to alignthe direction of maximum tension strength and stability with these linesof principle force or stress in the luff area as produced by thewind.Iaddend.. When panel 6 (warp threads 16) and panel 8 (warp threads18) form a triangle 19-22-20, with 22 being the sail centroid, it can beshown analytically that headstay stresses are reduced to less than halfthe loads encountered with prior art sails at a given wind velocity.

The result is an improved jib, of higher strength-to-weight ratio, whichdistributes stresses more evenly into the sail with less distortion fora given weight of cloth per square yard than any known prior art.

Seam stitching and sail edge finishing are performed in the conventionalmanner. Broad-seaming, the practice of sail shaping by tapered orbroadened seams, can also be applied in the conventional manner.

The first prototypes of this invention were constructed in July, 1982and first tested on Aug. 10, 1982.

I claim:
 1. An improved jib sail for a sailing yacht having a luffregion extending between the head and tack of said jib sail, said luffregion comprising upper and lower groups of triangular panels of wovencloth, each of said panels having an apex, a base, and a trailing edge,each of said panels further having warp threads extending substantiallyparallel to said trailing edge, said apex of each of said panels of saidupper group convergent at the head of said jib sail and said apex ofeach of said panels of said lower group convergent at the tack of saidjib sail, said base of each of said panels being joined along a commonseamline, said seamline being substantially perpendicular to the luff ofsaid jib sail and passing nearly through the locale of resultant windforce on said jib sail; wherein said warp threads provide maximum sailstrength along a line extending from the head of said jib sail into aregion near the locale of resultant wind force on said jib sail andthence to the tack of said jib sail thus producing a truss-likestructure of panels transferring the wind load to the head and tack,thereby reducing the need for headstay support.
 2. An improved jib sailas defined in claim 1, capable of improved windward performance over abroader wind speed range by virtue of its greater strength per givenweight of sail cloth.
 3. An improved jib sail as defined in claim 1,capable of improved windward performance for a longer lifetime due toits shape dependence upon threadline strength rather than cloth biasstrength. .Iadd.
 4. A fore and aft sail having a head, a tack, a clewand a luff area along a luff edge between the head and the tack,comprising, the luff area comprised of sail material means having linesof directional stability extending between the vicinity of the head andthe vicinity of the tack, at least a portion of said lines ofdirectional stability extending away from the vicinity of the head at asmall angle to the luff edge which angle faces the tack, at least aportion of said lines of directional stability extending away from thevicinity of the tack at a small angle to the luff edge which angle facesthe head, and said lines of directional stability extending at saidsmall angles for at least a portion of the distance between the head andthe tack, said lines of directional stability being a direction in whichthe sail material means has greater resistance to deformation undertension forces than in other directions. .Iaddend. .Iadd.
 5. A sail asclaimed in claim 4 wherein said lines of directional stability of thesail material means in said luff area are aligned substantially with thelines of principle stress extending between the vicinity of the head andthe vicinity of the tack when the sail is under wind load and properlytensioned. .Iaddend. .Iadd.6. A sail as claimed in claim 5 wherein saidsail material means includes a plurality of separate panels of a sailmaterial joined together to form the luff area. .Iaddend. .Iadd.7. Asail as claimed in claim 6 wherein said panels are cut from a wovenmaterial having a warp and weft, and said lines of directional stabilityare aligned with the warp or weft. .Iaddend. .Iadd.8. A sail as claimedin claim 7 wherein there are at least four said panels with a pair ofpanels in an upper area and a pair of panels in a lower luff area, eachpanel being substantially triangular with first and second long sidesand one short side and with the warp aligned with the first long side,and one panel of each pair having the second long side along the luffedge and the first long side joined to the second long side of the otherpanel of that pair. .Iaddend. .Iadd.9. A sail as claimed in claim 8wherein the short side of at least one panel in the upper luff area isjoined to the short side of at least one panel in the lower luff area..Iaddend. .Iadd.10. A sail as claimed in claim 5 wherein said sailmaterial means is a woven material having a warp and weft, and saidlines of principle stress and directional stability are aligned with thewarp or weft. .Iaddend. .Iadd.11. A sail as claimed in claim 4 whereinsaid sail material means includes a plurality of separate panels of asail material joined together to form the luff area. .Iaddend. .Iadd.12.A sail as claimed in claim 11 wherein said panels are cut from a wovenmaterial having a warp and weft, and said lines of directional stabilityare aligned with the warp or weft. .Iaddend. .Iadd.13. A fore and aftsail having a head, a tack, a clew, and a luff area along a luff edgebetween the head and tack, comprising, the luff area comprised of sailmaterial means having lines of directional stability in the direction ofwhich the sail material means has substantially greater resistance todeformation under tension than in most other directions, and said linesof directional stability extending between the vicinity of the head andthe vicinity of the tack with at least a substantial proportion of saidlines positioned at a small angle to the luff edge, said lines ofdirectional stability extending away from the vicinity of the head at asmall angle to the luff edge which angle faces the tack and said linesof directional stability extending away from the vicinity of the tack ata small angle to the luff edge which angles faces the head. .Iaddend..Iadd.14. The sail of claim 13 wherein said sail material means iscomprised of a plurality of elongated panels extending generally in thedirection between the head and the tack, and each panel is of a wovenmaterial having a warp and weft with the warp substantially aligned withsaid lines of directional stability. .Iaddend. .Iadd.15. A fore and aftsail having a head, a tack, a clew and a luff area along a luff edgebetween the head and the tack, comprising, the luff area comprised ofsail material means having lines of directional stability extendingbetween the vicinity of the head and the vicinity of the tack with atleast a portion of said lines of directional stability positioned at asmall angle to the luff edge for a portion of the distance between thehead and the tack, said lines of directional stability being a directionin which the sail material means has greater resistance to deformationunder tension forces than in other directions, said lines of directionalstability of the sail material means in said luff area being alignedsubstantially with the lines of principle stress extending between thevicinity of the head and the vicinity of the tack when the sail is underwind load and properly tensioned, said sail material means including aplurality of separate panels of a sail material joined together to formthe luff area with each of said panels being cut from a woven materialhaving a warp and weft, said lines of directional stability are alignedwith the warp or weft, at least four said panels with a pair of panelsin an upper area and a pair of panels in a lower luff area, each panelbeing substantially triangular with first and second long sides and oneshort side and with the warp aligned with the first long side, and onepanel of each pair having the second long side along the luff edge andthe first long side joined to the second long side of the other panel ofthat pair. .Iaddend. .Iadd.16. A sail as claimed in claim 15, whereinthe short side of at least one panel in the upper luff area is joined tothe short side of at least one panel in the lower luff area. .Iaddend..Iadd.17. An improved sail for a sailing yacht having a luff regionextending between the head and tack of said sail, said luff regioncomprising upper and lower groups of triangular panels of woven cloth,each of said panels having an appex, a base, and a trailing edge, eachof said panels further having warp threads extending substantiallyparallel to said trailing edge, said apex of each of said panels of saidupper group convergent at the head of said sail and said apex of each ofsaid panels of said lower group convergent at the tack of said sail,said base of each of said panels being joined along a common seamline,said seamline being substantially perpendicular to the luff of said sailand passing nearly through the locale of resultant wind force on saidsail; wherein said warp threads provide maximum sail strength along aline extending from the head of said sail into a region near the localeof resultant wind force on said sail and thence to the tack of said sailthus producing a truss-like structure of panels transferring the windload to the head and tack, thereby reducing the need for headstaysupport. .Iaddend. .Iadd.18. An improved sail as defined in claim 17,capable of improved windward performance over a broader wind speed rangeby virtue of its greater strength per given weight of sail cloth..Iaddend. .Iadd.19. An improved sail as defined in claim 17, capable ofimproved windward performance for a longer lifetime due to its shapedependence upon threadline strength rather than cloth bias strength..Iaddend.